A polyarylene sulfide (hereinafter, referred to as “PAS”) is a representative engineering plastic. Its demand is increasing for use in electronic products and various products used in high temperatures and in a corrosive environment by virtue of its high heat resistance, high chemical resistance, and high flame retardancy.
Polyphenylene sulfide (hereinafter, referred to as “PPS”) is the only commercially available product among such polyarylene sulfides. However, conventional PPS has a disadvantage in that its thermal conduction efficiency in the vertical direction is lower than that of other high-performance plastics despite its excellent mechanical and thermal properties. The thermal conductivity of the entire article molded from the conventional PPS, which has low thermal conductivity in the vertical direction, is lowered. The bigger the molded article is, the more the thermal conductivity thereof tends to decrease.
In order to improve the physical properties of PPS, a resin composition that comprises graphite as a thermally conductive filler in addition to PPS has been proposed (Korean Laid-open Patent Publication No. 2010-0075878). However, the resin composition disclosed in the above-cited patent publication has a poor thermal conductivity.
Especially, in order to improve the thermal conductivity of PPS, a composition that comprises a plate-shaped inorganic material having a high thermal conductivity in addition to PPS has been proposed in the prior art. In this composition, however, the thermal conductivity in the orientation direction of the added inorganic material is increased, whereas the thermal conductivity in the vertical direction to the orientation direction is low. In addition, a composition that comprises an insulative ceramic in a spherical shape such as alumina and magnesium oxide in addition to PPS has a similar thermal conductivity in the horizontal and vertical directions. However, the thermal conductivity of the added inorganic material itself is so low that it cannot satisfy the thermal conductivity required for the recent trend that electronic devices have become lighter, thinner, shorter, and smaller with high performance.
In the meantime, as the applicable range of a high heat dissipation material is expanded from electronic and communication devices to automobile parts, the size of molded articles is varied, and products having excellent heat conduction efficiency in the horizontal and vertical directions are required regardless of the size of the molded article.
Accordingly, there is a need to develop a resin composition, which improves thermal conductivity or insulation in the horizontal and vertical directions of the composition, has excellent thermal conductivity regardless of the size of a molded article, and minimizes deterioration of the physical properties of PPS.